An undervoltage release device is an accessory used with circuit protective apparatus to interrupt the circuit current when the systems voltage falls below a predetermined value. U.S. Pat. Nos. 4,301,434 and 4,467,299 describe such undervoltage release accessories and are incorporated herein for reference purposes.
Once the undervoltage condition has occurred and the undervoltage release has articulated the circuit breaker operating mechanism to interrupt the circuit current, it is essential that the systems voltage be restored before the circuit contacts are reclosed. When the undervoltage release condition is caused by a short circuit fault condition, the systems voltage is insufficient to energize the undervoltage release solenoid while the fault condition exists. When an attempt is made to close the circuit breaker contacts, there is a possibility that the circuit breaker contacts will close on a fault causing damage to the contacts, other circuit breaker components, and down-stream electrical apparatus. Accordingly, some means must be provided to insure that the undervoltage release solenoid is reset before the circuit breaker contacts are reclosed.
The undervoltage release arrangement of the instant invention prevents the circuit breaker operating mechanism from closing the circuit breaker contacts until and unless the undervoltage release solenoid is reset.